Concurrent Engineering requires a creative blend of basic research with design. This is particularly true for human-machine systems. Simulators provide both an opportunity and a challenge for basic research on human performance. Simulators provide an opportunity where researchers can manipulate goals, dynamics, and information in a way that will allow direct generalizations to operational environments. Simulators provide a challenge where human performance researchers must provide information with regard to critical design decisions — How much realism is necessary? How can the simulator be used most effectively in training?